Various types of valves incorporating sealing devices are known and widely used in the medical field. For example, mechanical sealing valves are required for various types of catheters, lavage devices, and endoscopy systems developed for a wide range of medical purposes. The valve sealing mechanisms typically preclude the flow of substances (gaseous or fluid) through the medical device in one direction, for example from the patient to the outside environment, while permitting the introduction or flow of desired substances (food, medication, etc.) in the other direction, for example into the patient through the medical device. Enteral feeding devices utilizing a gastrostomy catheter (“feeding tube”) are examples of conventional medical devices utilizing a sealing valve to prevent gastric fluids, gases, or particles from unintentionally exiting the patient's body via the catheter. U.S. Pat. Nos. 5,997,503 and 5,997,546, both owned by Applicants' Assignee and incorporated by reference herein, disclose balloon catheters suitable for use as skin-level gastrostomy catheters for enteral feeding. Various other devices and catheters have also been proposed for gastrostomy feeding and are known to those skilled in the art.
Conventional sealing valves include duckbill valves, flap valves, slit seal valves, etc. Silicone rubber duckbill seals having durometer ratings of about 50 Shore and a wall thickness of about 0.040 inches have been employed in sealing gastrostomy catheters. Such sealing valves are typically kept closed via back pressure present on one side of the valve unless and until the seal is opened from the other side of the valve by insertion of a feeding tube or by a pressure differential across the seal.
Over time, conventional sealing valves may degrade or lose some of their flexibility (i.e., their ability to return to an initial sealing position after deflection) due to repeated or extended periods of opening of the valve. Also, in certain bodily environments, such as the acidic environment of the gastrointestinal tract, exposure to bodily fluids or stomach contents may have a corrosive or other negative effect on the sealing valve over time.
Thus, there is a need for an improved medical sealing valve for use in various medical devices, particularly gastrostomy catheter devices.